Mechanism of the Photooxidation of Formaldehyde Studied by Flash Photolysis of CH2O-O2-NO Mixtures

Article abstract of DOI:10.1021/j100214a032

The mechanism of the chain process leading to formic acid in the photooxidation of CH2O has been studied with the flash photolysis technique.Mixtures of CH2O, O2, and NO were photolyzed and the rate of appearance and yield of NO2 were monitored.Kinetic simulations of both sets of data allowed the determination of the rate constants for the main reactions HO2 + CH2O -> O2CH2OH (6), OCH2OH + O2 -> HO2 + HCO2H (8), OCH2OH + NO -> products (9) (k₆=(7.5 +/-3.5)E-14; k₈=(3.5 +/-1.6)E-14; k₉=(4.0 +/-1.9)E-11 cm³molecule^-1s^-1).Quantum calculations provided estimates of the heats of formation for the radicals involved.The effect of temperature was investigated, suggesting the importance of the decomposition of the radical HOCH2O into H atom and formic acid.The validity of the global scheme is discussed along with its importance for the removal of CH2O and the production of formic acid in the athmosphere.